ForTheLoveOfNature

Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered.[2] The group, visible in the constellation Pegasus, was discovered by Édouard Stephan in 1877 at the Marseille Observatory.[3] The group is the most studied of all the compact galaxy groups.[2] The brightest member of the visual grouping is NGC 7320 that is shown to have extensive H II regions, identified as red blobs, where active star formation is occurring.

Four of the five galaxies in Stephan's Quintet form a physical association, Hickson Compact Group 92, and will likely merge with each other. Radio observations in the early 1970s revealed a mysterious filament of emission which lies in inter-galactic space between the galaxies in the group. This same region is also detected in the faint glow of ionized atomic hydrogen seen in the visible part of the spectrum as a green arc.

Two space telescopes have recently provided new insight into the nature of the filament, which is now believed to be a giant intergalactic shock-wave (similar to a sonic boom but traveling in intergalactic gas rather than air) caused by one galaxy (NGC 7318B) falling into the center of the group at several millions of kilometers per hour.

The Whirlpool Galaxy, also known as Messier 51a, M51a, and NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus.[7][6][8] It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy.[9] Its distance is estimated to be 23 million light-years away from Earth.

The galaxy and its companion, NGC 5195,[10] are easily observed by amateur astronomers, and the two galaxies may be seen with binoculars.[11] The Whirlpool Galaxy has been extensively observed by professional astronomers, who study it to understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions.

The Milky Way is the galaxy[nb 1] that contains the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος (galaxías kýklos, "milky circle").[17][18][19] From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from its outer rim. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe.[20] Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis,[21] observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

The Milky Way is a barred spiral galaxy with a diameter between 150,000 and 200,000 light-years (ly).[22][23][24][25] It is estimated to contain 100–400 billion stars[26][27] and more than 100 billion planets.[28][29] The Solar System is located at a radius of 26,490 (± 100) light-years from the Galactic Center, on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust. The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The galactic center is an intense radio source known as Sagittarius A*, assumed to be a supermassive black hole of 4.100 (± 0.034) million solar masses.

Pillars of Creation is a photograph taken by the Hubble Space Telescope of elephant trunks of interstellar gas and dust in the Eagle Nebula, specifically the Serpens constellation, some 6,500–7,000 light years from Earth.[1] They are so named because the gas and dust are in the process of creating new stars, while also being eroded by the light from nearby stars that have recently formed.[2] Taken on April 1, 1995, it was named one of the top ten photographs from Hubble by Space.com.[3] The astronomers responsible for the photo were Jeff Hester and Paul Scowen from Arizona State University. The region was rephotographed by ESA's Herschel Space Observatory in 2011, and again by Hubble in 2014 with a newer camera.

The Eagle Nebula (catalogued as Messier 16 or M16, and as NGC 6611, and also known as the Star Queen Nebula and The Spire) is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Chéseaux in 1745–46. Both the "Eagle" and the "Star Queen" refer to visual impressions of the dark silhouette near the center of the nebula,[3][4] an area made famous as the "Pillars of Creation" imaged by the Hubble Space Telescope. The nebula contains several active star-forming gas and dust regions, including the aforementioned Pillars of Creation.

Two jets of particles fly out from a newborn star in the Orion B molecular cloud, some 1,350 light years from Earth. Though the star itself is veiled by dust, its glow lights up the whole region.

When stars form within giant clouds of cool molecular hydrogen, some of the surrounding material collapses under gravity to form a rotating, flattened disk encircling the newborn star. Though planets may later congeal in the disk, at this early stage the protostar is feeding on the disk. Gas from the disk rains down onto the protostar and engorges it. Superheated material spills away and is shot outward from the star in opposite directions along an uncluttered escape route – the star’s rotation axis.

Shock fronts develop along the jets and heat the surrounding gas. The jets collide with the surrounding gas and dust and clear vast spaces, like a stream of water ploughing into a hill of sand.

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Tarantula Nebula, also called 30 Doradus, (catalog number NGC 2070) immense ionized-hydrogen region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way system (in which Earth is located). The nebula consists of a cloud of interstellar gas—principally hydrogen—lit from within by young, hot stars that ionize the gas around them. As the atoms in the gas recombine, they emit visible light. The total mass of the nebula is about 1,000,000 solar masses, and its diameter is 170 parsecs (550 light-years), making it the largest region of ionized gas in the entire Local Group of galaxies.

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The Carina Nebula (catalogued as NGC 3372; also known as the Grand Nebula, Great Nebula in Carina, or Eta Carinae Nebula) is a large, complex area of bright and dark nebulosity in the constellation Carina, and is located in the Carina–Sagittarius Arm. The nebula lies at an estimated distance of approximately 8,500 light-years (2,600 pc) from Earth.

The nebula has within its boundaries the large Carina OB1 association and several related open clusters, including numerous O-type stars and several Wolf–Rayet stars. Carina OB1 encompasses the star clusters Trumpler 14 and Trumpler 16. Trumpler 14 is one of the youngest known star clusters at half a million years old. Trumpler 16 is the home of WR 25, currently the most luminous star known in our Milky Way galaxy, together with the less luminous but more massive and famous Eta Carinae star system and the O2 supergiant HD 93129A. Trumpler 15, Collinder 228, Collinder 232, NGC 3324, and NGC 3293 are also considered members of the association. NGC 3293 is the oldest and furthest from Trumpler 14, indicating sequential and ongoing star formation.

The Carina Nebula (catalogued as NGC 3372; also known as the Grand Nebula, Great Nebula in Carina, or Eta Carinae Nebula) is a large, complex area of bright and dark nebulosity in the constellation Carina, and is located in the Carina–Sagittarius Arm. The nebula lies at an estimated distance of approximately 8,500 light-years (2,600 pc) from Earth.

The nebula has within its boundaries the large Carina OB1 association and several related open clusters, including numerous O-type stars and several Wolf–Rayet stars. Carina OB1 encompasses the star clusters Trumpler 14 and Trumpler 16. Trumpler 14 is one of the youngest known star clusters at half a million years old. Trumpler 16 is the home of WR 25, currently the most luminous star known in our Milky Way galaxy, together with the less luminous but more massive and famous Eta Carinae star system and the O2 supergiant HD 93129A. Trumpler 15, Collinder 228, Collinder 232, NGC 3324, and NGC 3293 are also considered members of the association. NGC 3293 is the oldest and furthest from Trumpler 14, indicating sequential and ongoing star formation.

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion.[b] It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years[3][6] and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light years across. It has a mass of about 2,000 times that of the Sun. Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula.

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion.[b] It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years[3][6] and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light years across. It has a mass of about 2,000 times that of the Sun. Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula.

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion.[b] It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years[3][6] and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light years across. It has a mass of about 2,000 times that of the Sun. Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula.

The Helix Nebula, also known as NGC 7293, is a planetary nebula (PN) located in the constellation Aquarius. Discovered by Karl Ludwig Harding, probably before 1824, this object is one of the closest to the Earth of all the bright planetary nebulae.[5] The distance, measured by the Gaia mission, is 655±13 light-years[6]. It is similar in appearance to the Cat's Eye Nebula and the Ring Nebula, whose size, age, and physical characteristics are similar to the Dumbbell Nebula, varying only in its relative proximity and the appearance from the equatorial viewing angle.[7] The Helix Nebula has sometimes been referred to as the "Eye of God" in pop culture,[8] as well as the "Eye of Sauron".

The Helix Nebula, also known as NGC 7293, is a planetary nebula (PN) located in the constellation Aquarius. Discovered by Karl Ludwig Harding, probably before 1824, this object is one of the closest to the Earth of all the bright planetary nebulae.[5] The distance, measured by the Gaia mission, is 655±13 light-years[6]. It is similar in appearance to the Cat's Eye Nebula and the Ring Nebula, whose size, age, and physical characteristics are similar to the Dumbbell Nebula, varying only in its relative proximity and the appearance from the equatorial viewing angle.[7] The Helix Nebula has sometimes been referred to as the "Eye of God" in pop culture,[8] as well as the "Eye of Sauron".

The Horsehead Nebula (also known as Barnard 33) is a small dark nebula in the constellation Orion.[2] The nebula is located just to the south of Alnitak, the easternmost star of Orion's Belt, and is part of the much larger Orion Molecular Cloud Complex. It appears within the southern region of the dense dust cloud known as Lynds 1630, along the edge of the much larger HII nebula region called IC 434.[1]

The Horsehead Nebula is approximately 460 parsecs or 1400 light years from Earth.[1] It is one of the most identifiable nebulae because of its resemblance to a horse's head.

Mystic Mountain is a photograph and a term for a region in the Carina Nebula imaged by the Hubble Space Telescope. The view was captured by the then-new Wide Field Camera 3, though the region was also viewed by the previous generation instrument. The new view celebrated the telescope's 20th anniversary of being in space in 2010.[1] Mystic Mountain contains multiple Herbig-Haro objects where nascent stars are firing off jets of gas which interact with surrounding clouds of gas and dust.[2][3]

This region is about 7,500 light-years (2,300 pc) away from Earth. The pillar measures around three light-years in height (190,000 astronomical units).

Mystic Mountain is a photograph and a term for a region in the Carina Nebula imaged by the Hubble Space Telescope. The view was captured by the then-new Wide Field Camera 3, though the region was also viewed by the previous generation instrument. The new view celebrated the telescope's 20th anniversary of being in space in 2010.[1] Mystic Mountain contains multiple Herbig-Haro objects where nascent stars are firing off jets of gas which interact with surrounding clouds of gas and dust.[2][3]

This region is about 7,500 light-years (2,300 pc) away from Earth. The pillar measures around three light-years in height (190,000 astronomical units).

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NGC 7006 resides in the outskirts of the Milky Way. It is about 135 000 light-years away, five times the distance between the Sun and the centre of the galaxy, and it is part of the galactic halo. This roughly spherical region of the Milky Way is made up of dark matter, gas and sparsely distributed stellar clusters.

Like other remote globular clusters, NGC 7006 provides important clues that help astronomers to understand how stars formed and assembled in the halo. The cluster now pictured by Hubble has a very eccentric orbit indicating that it may have formed independently, in a small galaxy outside our own that was then captured by the Milky Way.

Although NGC 7006 is very distant for a Milky Way globular cluster, it is much closer than the many faint galaxies that can be seen in the background of this image. Each of these faint smudges is probably accompanied by many globular clusters similar to NGC 7006 that are too faint to be seen even by Hubble.

NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an H II region[1] emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52. The "bubble" is created by the stellar wind from a massive hot, 8.7[1] magnitude young central star, SAO 20575 (BD+60°2522).[7] The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow.[7] It was discovered in 1787 by William Herschel.[5] The star BD+60°2522 is thought to have a mass of about 44 M☉.

NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an H II region[1] emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52. The "bubble" is created by the stellar wind from a massive hot, 8.7[1] magnitude young central star, SAO 20575 (BD+60°2522).[7] The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow.[7] It was discovered in 1787 by William Herschel.[5] The star BD+60°2522 is thought to have a mass of about 44 M☉.

Arp 273 is a pair of interacting galaxies, lying 300 million light years away in the constellation Andromeda. It was first described in the Atlas of Peculiar Galaxies, compiled by Halton Arp in 1966. The larger of the spiral galaxies, known as UGC 1810, is about five times more massive than the smaller galaxy.

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